This invention relates to an information retrieval apparatus for retrieving user's desired data from a database.
There is known an information retrieval apparatus for a user to retrieve desired data from a database, in which the user inputs a part of a target name as characters, and the apparatus provides the user with data matching the input characters so that the user can select the data to finish the task.
As a typical one, there is a task of setting a destination in a car navigation system.
A car navigation system uses information retrieval interface as described above for retrieving POI (Point Of Interest) names and place names existing enormously on a nationwide scale so as to set a destination. In this information retrieval, the user first inputs a part of the POI name via a touch panel or a remote controller of the car navigation system. After that, when a retrieval button is pressed, a list of POI names including the character string input by the user is displayed, and the destination can be set when the user selects one of the listed POI names.
However, there is an enormous number of POIs on a nationwide scale, and hence the number of POI names matching the character string input as a part of the POI name by the user may be greatly large in many cases. Therefore, the user may be required to scroll or to do other operations for viewing all the candidates even when the list of the POI names is displayed. Thus, it may take the user a long period of time to find a desired POI.
To solve this problem, Japanese Patent Application Laid-open No. 2002-107173 discloses a technology of decreasing the number of candidate POIs by providing means for inputting a place name or a POI's category in addition to the means for inputting a POI name as a character string. In addition, Japanese Patent Application Laid-open No. 2006-202159 discloses a technology of changing an attribute for narrowing candidates of contents in content retrieval of a database, based on a retrieval strategy.
Japanese Patent Application Laid-open No. 2004-234421 discloses a technology in a website retrieval apparatus as follows. If the number of items as a result of retrieval is larger than a predetermined number so that the items cannot be displayed on a screen, keywords included in the websites of the retrieval result are shown to the user so that the user can select the keyword. Thus, the websites are narrowed to ones including the keyword selected by the user.